Ssrs 2012 export problem to excel

In an ssrs 2012, there is an problem when the report is exported to excel when running on a ssrs 2012 report server. When the report is generated, selected cells are highlighted. When the report is exported to a PDF file, the correct selected cells are highlighted with a background color.

However when the report is exported to excel on the report server, all cells are highlited from the first point of where the individual cells are highlighted to the end of the data. For example, if row # 5 has a cell highligted in column D then all rows from row #5 to the end have in column D are incorrectly highlighted.

When I run the rdl on my workstation, there are no export problems. The report server exports excel files to an *.xls file and my workstation also exports the excel file to an *.xls file also. However I do have office 2013 on my workstation.
Note: The code that is causing this highlight the background color for a cell is the following:

=IIF(Fields!IndicatorCount12.Value > 0, "LightSteelBlue" , nothing). This is the code in the background property of the applicable cell.

Thus would you tell me and/or point me to a url that will tell me how to solve this problem?

this is a Microsoft known issue